Fungus kills frogs by dehydration

A fungus that has torn through frog populations worldwide kills by dehydrating the hapless amphibians, disrupting electrolyte balance and causing cardiac arrest.

The fungus Batrachochytrium dendrobatidis, which is responsible for chytridiomycosis disease, has caused massive frog death on a global scale, threatening many species with extinction. When the fungus reached the Sierra Nevada mountains in California, it slashed mountain yellow-legged frog populations by more than 75 percent in only about four years. The frog (Rana muscosa) is now listed as endangered.

Laboratory experiments had established how the fungus operates, but a new study is the first to observe the disease in action in the wild. San Francisco State University biologist Vance Vredenburg and colleagues collected blood samples and skin swabs from more than 100 yellow-legged frogs over the course of the summer of 2004, the year the outbreak hit the Sierra region.